This invention generally relates to an arrangement for sealing an interface between a rotating shaft and a stationary housing.
Automotive vehicles include rotary shafts that are at least partially received in and rotate relative to a stationary housing. Examples of such arrangements are found in conventional transmissions and axle assemblies. It is necessary to provide a seal at the interface between the shaft and the housing. Sealing the interface is necessary because under many driving conditions, especially during rain, large amounts of contaminants are present that could enter into the interface between the shaft and the housing and cause eventual problems.
Conventional sealing arrangements typically include a rubber lip seal to prevent contaminants from entering into the system. Further, the rubber lip seals are used to keep lubricant from exiting the system. There are several problems with conventional rubber lip seals. First, rubber lip seals tend to wear out in an undesirable fashion. The rotary shafts on most vehicles rotate at very high speeds and the constant contact between the rotating shaft and the rubber lip seal causes the seal to wear. Further, the presence of contaminants along the contact area between the shaft and the rubber lip seal often cause significant wear on the seal, resulting in short seal life. A further problem exists in that the rotary shafts have some radial and axial movement relative to the housing. With conventional lip seals, such movement is not compensated for and, a proper seal is not maintained. Under these conditions, it is more likely that outside contaminants will enter into the shaft and housing interface and, moreover, become lodged between the lip seal and the shaft resulting in faster wear-out of the seal.
Therefore, it is desirable to provide an improved sealing device for sealing the interface between a rotary shaft and a stationary housing. This invention provides a sealing device that overcomes the shortcomings and drawbacks of the prior art discussed above.
In general terms, this invention is a sealing device for sealing off an interface between a rotary shaft and a stationary housing. The sealing device of this invention takes several forms.
In one embodiment, a first seal is supported near the interface between the rotary shaft and the stationary housing. The first seal includes a plurality of propeller portions that create a fluid disturbance near the interface as the first seal rotates with the shaft. A second seal is supported to remain stationary with the stationary housing. The second seal includes a first end that is supported on the stationary housing and a second end that includes a contact surface, which contacts a peripheral surface on the rotating shaft. A biasing member biases the contact surface toward the peripheral surface on the shaft. The second seal also includes a generally flexible connecting portion that extends between the first and second ends on the second seal. The generally flexible connecting portion preferably has a bellows-shaped configuration so that it flexes in response to radial and axial movements of the shaft relative to the stationary housing. When the generally flexible connecting portion flexes, the contact surface of the second seal remains in the desirable contact with the peripheral surface on the shaft.